A method for testing the tensile properties of titanium alloy wire

Abstract

The present invention discloses a method for detecting the tensile properties of titanium alloy wire, which relates to the technical field of material detection, and includes the following steps: S1, preparing a sample and pre-detecting a microstructure; S2, performing equalization processing on the distribution of pre-tensile stress; S3, determining the area where local plastic deformation of the sample may occur; S4, performing dynamic tensile load increment control; S5, introducing displacement field analysis and performing data correction; S6, performing microcrack monitoring; S7, performing fracture mechanism analysis and fracture morphology characterization; S8, constructing a dynamic damage evolution model. This method avoids the experimental error caused by constant rate loading in traditional methods by effectively simulating the complex loading conditions of titanium alloy wire in actual use. Combined with the dynamic correction of stress-strain data and microcrack monitoring technology, it is possible to capture the key behaviors of the material such as yielding, plastic deformation, and crack extension under different loading conditions in real time, thereby accurately evaluating its tensile properties.

Description

Technical Field

[0001] The invention relates to the technical field of material detection, and in particular to a method for detecting the tensile properties of a titanium alloy wire. Background Art

[0002] Titanium alloy wires are widely used in aerospace, medical equipment, and high-performance industrial equipment due to their excellent high-temperature strength, corrosion resistance, and good biocompatibility. Their application in these fields requires them to have extremely high tensile strength and good ductility, so accurate testing of the tensile properties of titanium alloy wires is crucial.

[0003] Traditional methods for testing the tensile properties of titanium alloy wires mostly use standard tensile tests, which stretch the material at a constant loading rate to obtain a stress-strain curve. Although these methods can provide preliminary tensile strength data, they often cannot fully reflect the behavioral characteristics of the material under complex loading conditions during the loading process. Especially for high-strength titanium alloy wires, standard constant-rate loading may not accurately capture key properties such as yield, fracture, and microcrack propagation. Therefore, traditional tensile performance testing methods have certain deficiencies in accuracy, applicability, and reliability. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for detecting the tensile properties of a titanium alloy wire to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a method for detecting the tensile properties of a titanium alloy wire, comprising the following steps:

[0007] S1. Prepare the sample and pre-test the microstructure of titanium alloy wire to provide preliminary material information for tensile performance testing;

[0008] S2. Perform pre-stretching stress distribution equalization on the specimen to avoid errors caused by initial residual stress;

[0009] S3. Determine the area where the sample may undergo local plastic deformation and perform precise positioning to avoid the overall tensile results being affected by local strain concentration characteristics;

[0010] S4, after locating the area where the sample may undergo local plastic deformation, dynamic tensile load increment control is performed to obtain stress-strain data;

[0011] S5. After obtaining stress-strain data, displacement field analysis is introduced to perform data correction to avoid errors caused by sample clamping.

[0012] S6. After the sample enters the plastic deformation stage, the damage evolution characteristics of the material are determined by microcrack monitoring technology to obtain the fracture characteristics;

[0013] S7. Perform fracture mechanism analysis and fracture morphology characterization based on fracture characteristics to obtain fracture mechanism data;

[0014] S8. Based on stress-strain data, fracture characteristics, and fracture mechanism data, a dynamic damage evolution model is constructed to predict the tensile properties of materials under different loads and loading rates.

[0015] To further optimize the technical solution, in step S2, when performing the pre-stretching stress distribution equalization process, the stress state of the sample is firstly modeled;

[0016] In order to eliminate the residual stress introduced in the specimen during the manufacturing process, it is assumed that the distribution of the initial residual stress of the specimen during the pre-stretching process is an uneven stress field, and as the pre-stretching proceeds, the residual stress gradually decreases and tends to a balanced state; this process is described by the initial stress distribution model, the stress distribution model after pre-stretching, and the balanced stress state model.

[0017] Further optimizing the technical solution, the initial stress distribution model is used to describe the inhomogeneity of the initial stress distribution in three-dimensional space, and the residual stress is concentrated on the surface or internal area of ​​the sample;

[0018] The initial stress distribution model is as follows:

[0019] ;

[0020] in,

[0021] Indicates that the sample is in position Initial residual stress at

[0022] is the maximum value of the initial residual stress;

[0023] It is an attenuation factor related to material processing, which determines the attenuation rate of residual stress in space;

[0024] is the spatial coordinate inside the specimen.

[0025] To further optimize the technical solution, the stress distribution model after pre-stretching is as follows:

[0026] ;

[0027] in,

[0028] Indicates at time When the sample is at position stress at

[0029] is a time constant that describes the decay rate of stress over time during pre-stretching;

[0030] It is the time of pre-stretching treatment;

[0031] This model is used to show that over time As time goes by, the stress in the specimen tends to be evenly distributed, and the intensity of the residual stress gradually decreases until it reaches a predetermined equilibrium state.

[0032] To further optimize the technical solution, the balanced stress state model is as follows:

[0033] ;

[0034] Indicates the balanced stress distribution after pre-stretching treatment;

[0035] It means that the residual stress is finally reduced to half of the initial value and reaches a balanced state;

[0036] After the specimen has been fully pre-stretched, the stress inside the material tends to be uniform and is described using the above model state.

[0037] To further optimize the technical solution, in step S3, the method for determining the area where local plastic deformation may occur includes:

[0038] Use digital imaging technology to perform high-precision full-field strain measurement on the sample surface, and combine finite element analysis to predict strain concentration areas;

[0039] If an obvious local strain concentration area is detected, the microstructure observation results are compared to determine whether the abnormal deformation is caused by defects and adjust the specimen sampling position.

[0040] To further optimize the technical solution, in step S4, the dynamic tensile load increment control includes:

[0041] In the initial stage of the material, a constant loading rate of 5% lower than the material yield strength is used per unit time to ensure that the relationship between stress and strain can change linearly; the loading rate is within the elastic region of the titanium alloy, and 5% to 15% of the material yield strength is selected as the loading rate per unit time to ensure that before the yield strength is reached, the specimen is not affected by stress concentration where the local stress exceeds 150%-200% of the material yield strength;

[0042] Once the material enters the yield stage, the loading rate is gradually increased; as plastic deformation occurs, the material begins to have the ability to withstand deformation exceeding 5%-10% plastic deformation, thereby ensuring that stress-strain data are captured during the tensile test by gradually increasing the loading rate.

[0043] To further optimize the technical solution, in step S5, during the stretching process, the clamping method of the sample leads to stress concentration at the end, which affects the measurement accuracy. During the displacement field analysis, the displacement-stress relationship is dynamically corrected:

[0044] Use a high-precision laser rangefinder or optical measuring instrument to monitor the deformation displacement of the sample in real time during loading, and calculate and correct the measurement error caused by clamping;

[0045] High-precision strain gauges are used to measure local strain at different locations and compared with the overall tensile curve to adjust the accuracy of the stress-strain curve.

[0046] To further optimize the technical solution, in step S6, when the titanium alloy wire reaches the yield limit, internal microcracks begin to initiate and expand;

[0047] Acoustic emission detection technology is used to monitor the time and location of crack formation in real time, and X-ray diffraction is used to analyze the lattice distortion inside the sample to determine the critical point of microcrack formation;

[0048] By analyzing the damage evolution process of titanium alloy, the fracture characteristics are obtained and the fatigue life of the material is predicted.

[0049] To further optimize the technical solution, in step S8, the dynamic damage evolution model includes:

[0050] Data correction damage model based on dynamic tensile load increment control method;

[0051] Analytical model of the relationship between fracture characteristics and loading rate;

[0052] Model for predicting failure behavior of titanium alloy wire.

[0053] In a second aspect, an embodiment of the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of a method for detecting the tensile properties of a titanium alloy wire as described in the first aspect of the present invention are implemented.

[0054] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, the steps of a method for detecting the tensile properties of a titanium alloy wire as described in the first aspect of the present invention are implemented.

[0055] Compared with the prior art, the present invention provides a method for detecting the tensile properties of titanium alloy wire, which has the following beneficial effects:

[0056] This method for testing the tensile properties of titanium alloy wire effectively simulates the complex loading conditions of titanium alloy wire in actual use, avoiding the test errors caused by constant rate loading in traditional methods. Combined with dynamic correction of stress-strain data and microcrack monitoring technology, it can capture key behaviors such as yield, plastic deformation, and crack extension of materials under different loading conditions in real time, thereby accurately evaluating their tensile properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0058] Figure 1 The present invention is a schematic flow chart of a method for testing the tensile properties of titanium alloy wire. DETAILED DESCRIPTION

[0059] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0060] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0061] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0062] Embodiment 1:

[0063] Reference Figure 1, which is the first embodiment of the present invention, provides a method for detecting the tensile properties of a titanium alloy wire, comprising the following steps:

[0064] S1. Prepare the sample and pre-test the microstructure of titanium alloy wire to provide preliminary material information for tensile performance testing.

[0065] In this embodiment, before the tensile performance test is performed, it is first necessary to prepare a sample of the titanium alloy wire. The size of the sample should meet the requirements of the experimental equipment, and surface defects or stress concentration points should be avoided to affect the experimental results. After the sample is prepared, a scanning electron microscope (SEM) or an optical microscope (OM) is used to observe the microstructure, focusing on the grain size, inclusions, phase distribution, etc. The elemental composition is analyzed using an energy dispersive spectrometer (EDS) to ensure that the alloy composition is uniform. If the structure is abnormal or inhomogeneous, it is necessary to adjust the sampling method or re-prepare the sample. The microstructure detection in this step not only provides preliminary material information for subsequent tensile tests, but also avoids experimental errors caused by sample defects.

[0066] S2. Perform pre-stretching stress equalization on the specimen to avoid errors caused by initial residual stress.

[0067] Titanium alloy wire may generate residual stress during the manufacturing process, which will affect the accuracy of tensile testing. Therefore, it is necessary to pre-stretch the specimen to balance the stress distribution. Low load pre-stretching (about 10-15% of the material's yield strength) is used to eliminate residual stress while maintaining the integrity of the material's internal structure. The strain distribution of the specimen is monitored by digital image correlation technology (DIC) or strain gauges to ensure residual stress equalization. In addition, heat treatment methods (such as low temperature aging) are combined to further stabilize internal stress to prevent the experimental data from being affected by processing residual stress. This step ensures the accuracy of the tensile test and improves the credibility of the tensile performance data.

[0068] In this embodiment, when performing the pre-stretching stress distribution equalization process, the stress state of the sample is firstly modeled;

[0069] In order to eliminate the residual stress introduced in the specimen during the manufacturing process, it is assumed that the distribution of the initial residual stress of the specimen during the pre-stretching process is an uneven stress field, and as the pre-stretching proceeds, the residual stress gradually decreases and tends to a balanced state; this process is described by the initial stress distribution model, the stress distribution model after pre-stretching, and the balanced stress state model.

[0070] Furthermore,

[0071] The initial stress distribution model is used to describe the inhomogeneity of the initial stress distribution in three-dimensional space, and the residual stress is concentrated on the surface or internal area of ​​the specimen;

[0072] The initial stress distribution model is as follows:

[0073] ;

[0074] in,

[0075] Indicates that the sample is in position Initial residual stress at

[0076] is the maximum value of the initial residual stress;

[0077] It is an attenuation factor related to material processing, which determines the attenuation rate of residual stress in space;

[0078] is the spatial coordinate inside the specimen.

[0079] The stress distribution model after pre-stretching is as follows:

[0080] ;

[0081] in,

[0082] Indicates at time When the sample is at position stress at

[0083] is a time constant that describes the decay rate of stress over time during pre-stretching;

[0084] It is the time of pre-stretching treatment;

[0085] This model is used to show that over time As time goes by, the stress in the specimen tends to be evenly distributed, and the intensity of the residual stress gradually decreases until it reaches a predetermined equilibrium state.

[0086] The equalized stress state model is as follows:

[0087] ;

[0088] Indicates the balanced stress distribution after pre-stretching treatment;

[0089] It means that the residual stress is finally reduced to half of the initial value. At this time, the material releases the local excessive stress, so that the overall stress distribution tends to be more uniform, indicating that the stress distribution inside the material tends to be uniform and reaches equilibrium;

[0090] After the specimen has been fully pre-stretched, the stress inside the material tends to be uniform and is described using the above model state.

[0091] In practice, the process of using the above model can be divided into the following steps:

[0092] Initial Stress Analysis:

[0093] Through preliminary stress testing (such as X-ray diffraction technology), we can obtain the initial stress distribution of titanium alloy wire without pre-stretching , and through the parameters in the model and To describe the spatial distribution characteristics of residual stress.

[0094] Apply low load pre-stretching:

[0095] Apply a low load (about 10-15% of the yield strength) to the specimen and record the stress changes during the pre-stretching process. , you can use and time To adjust the model and simulate the process of stress gradually tending to equilibrium.

[0096] Real-time monitoring of stress changes:

[0097] During the pre-stretching process, the strain distribution on the specimen surface is monitored using strain gauges or digital image correlation (DIC) technology. , we can know the changes of residual stress at different time points.

[0098] Final stress equalization:

[0099] As the pre-stretching time increases, the residual stress inside the specimen gradually becomes uniform and eventually reaches a balanced state. To predict the final stress state after treatment and ensure that the residual stress of the specimen is reduced to a reasonable range.

[0100] Through the above model, experimenters can adjust the pre-stretching conditions in real time and effectively monitor the changes in residual stress to ensure the reliability and consistency of the test data, which helps to optimize the test process and improve the accuracy of tensile performance testing.

[0101] S3. Determine the area where the sample may undergo local plastic deformation and perform precise positioning to avoid the overall tensile results being affected by local strain concentration characteristics. Use optical or computational methods to determine the area where local plastic deformation may occur, providing a precise measurement area for subsequent experimental data collection.

[0102] In this embodiment, during the stretching process of the titanium alloy wire, the plastic deformation is often not evenly distributed, but concentrated in specific areas, such as micro defects, weakly bonded areas at grain boundaries, etc. The method for determining the area where local plastic deformation may occur includes:

[0103] Use digital imaging technology to perform high-precision full-field strain measurement on the sample surface and capture the tiny deformation of the sample surface in real time. Generate a strain distribution map on the sample surface to accurately identify strain concentration areas, which usually correspond to plastic deformation of the material. The strain distribution map can help determine which areas have exceeded the elastic range and entered the plastic deformation stage. Then combine finite element (FEA) analysis to predict strain concentration areas;

[0104] If an obvious local strain concentration area is detected, the microstructure observation results are compared to determine whether it is an abnormal deformation caused by a defect, and the sample sampling position is adjusted. This step improves the accuracy of the tensile test data and ensures that the final tensile performance data represents the true performance of the entire material, rather than local characteristics.

[0105] S4. After locating the area where local plastic deformation may occur in the sample, dynamic tensile load increment control is performed to obtain stress-strain data. Traditional tensile tests usually use uniform loading, but for high-strength materials such as titanium alloy wire, the loading rate has a greater impact on the test results. This step adjusts the loading step in real time by loading, and combines the high-frequency measurement system to record the true stress-strain curve to ensure that key data (such as yield strength, maximum stress, and elongation at break) are accurate. This step effectively improves the reliability of tensile performance data while reducing the risk of abnormal fracture of the sample during the test.

[0106] In this embodiment, the dynamic tensile load increment control includes:

[0107] In the initial stage of the material, a constant loading rate of 5% lower than the material yield strength is used per unit time to ensure that the relationship between stress and strain can change linearly; the loading rate is within the elastic region of the titanium alloy, and 5% to 15% of the material yield strength is selected as the loading rate per unit time to ensure that before the yield strength is reached, the specimen is not affected by stress concentration where the local stress exceeds 150%-200% of the material yield strength;

[0108] Once the material enters the yield stage, the loading rate is gradually increased; as plastic deformation occurs, the material begins to have the ability to withstand deformation exceeding 5%-10% plastic deformation, thereby ensuring that stress-strain data are captured during the tensile test by gradually increasing the loading rate.

[0109] The loading rate change of the dynamic load increment control method can be expressed by the following mathematical model:

[0110] Constant rate loading before yielding:

[0111] Before yielding, the load Over time The model changes are:

[0112] ;

[0113] in:

[0114] It's time Load at time;

[0115] is the initial load (usually zero or a small preload);

[0116] is the constant loading rate coefficient, which is usually selected to make the stress-strain curve of the specimen linear at this stage.

[0117] is the time, which in this model represents the duration of the loading process.

[0118] Gradual acceleration loading after yielding:

[0119] Once the material yields and enters the plastic deformation stage, the loading rate increases. The relationship between load and time is now expressed using an exponential growth model:

[0120] ;

[0121] in:

[0122] is the load at the yield point of the material.

[0123] It is the incremental coefficient of gradually increasing the loading speed, which determines the degree of increase in the loading rate.

[0124] It is an exponential attenuation coefficient related to material properties, loading equipment and experimental environment.

[0125] By formula Calculate the stress where The sample is at time The cross-sectional area at the time of the test (taking into account the deformation of the specimen, the cross-sectional area changes with time). Based on the relationship between stress and strain, an accurate stress-strain curve can be obtained.

[0126] When used in actual operations, it includes:

[0127] Choose the appropriate loading rate:

[0128] Before the yield point of the specimen, the yield strength of the titanium alloy wire is determined through preliminary material testing or literature data. Based on this, the loading rate is set and , ensuring that the loading rate in the initial stage will not cause local damage or excessive deformation of the specimen, while ensuring that the plastic deformation process of the material can be accurately captured after yielding.

[0129] Loading system control:

[0130] Use precise servo loading system and load control system to monitor and adjust load changes in real time. Dynamically adjust the loading rate to ensure that the loading speed is gradually increased after yielding in order to capture the deformation process after yielding. The system also needs to provide real-time feedback of the specimen deformation data so that necessary adjustments can be made during the experiment.

[0131] Data collection and analysis:

[0132] During the entire test process, the stress-strain curve is collected in real time, with particular attention paid to the relationship between stress and strain before and after the yield point. High-precision strain gauges or digital image correlation technology (DIC) are used to monitor the local deformation of the specimen to ensure that all deformation characteristics before the yield point and fracture can be accurately recorded. In addition, frequency response analysis is used to ensure that changes in loading rate will not cause excessive noise or interference, ensuring the accuracy of the experimental data.

[0133] Specimen monitoring and stress concentration control:

[0134] In the test, a high-frequency measurement system is used to monitor the local strain distribution of the specimen in real time. Especially after yielding, the deformation of the specimen will be concentrated in certain areas, which may lead to early fracture. By controlling the increase in loading rate, excessive loading can be avoided to avoid sudden rupture of the specimen, thereby increasing the stability and safety of the test.

[0135] S5. After obtaining stress-strain data, displacement field analysis is introduced to perform data correction to avoid errors caused by sample clamping.

[0136] In this embodiment, during the stretching process, the clamping method of the sample leads to stress concentration at the end, which affects the measurement accuracy. The displacement-stress relationship is dynamically corrected during the displacement field analysis:

[0137] Use a high-precision laser rangefinder or optical measuring instrument to monitor the deformation displacement of the sample in real time during loading, calculate and correct the measurement error caused by the clamping effect. First, it is necessary to identify the stress concentration effect in the clamping area. Through theoretical analysis and finite element simulation, determine the stress distribution in the clamping area, and estimate the strain deviation in the area. Then, use the local strain measurement data to correct the strain measurement value of the clamping area. Finally, by adjusting the overall stress-strain curve, the clamping effect is corrected to a uniform stress state to ensure that the true material tensile performance data is obtained;

[0138] High-precision strain gauges are used to measure local strain at different locations and compare them with the overall tensile curve to adjust the accuracy of the stress-strain curve. First, local strain measurements (such as strain gauges) are used to compare the strain differences between the clamping area and the free area to identify and quantify the impact of the clamping effect. Then, the corrected strain data is fused with the original stress-strain curve, and numerical correction methods (such as interpolation or smoothing algorithms) are applied to adjust the stress-strain curve to eliminate the error caused by clamping. Ultimately, the generated correction curve can accurately reflect the true tensile properties of the material and ensure the reliability and validity of the test results. This step ensures the authenticity of the experimental data, making the obtained parameters such as tensile strength and yield strength more valuable for reference.

[0139] S6. After the sample enters the plastic deformation stage, the damage evolution characteristics of the material are determined through microcrack monitoring technology to obtain the fracture characteristics.

[0140] In this embodiment, when the titanium alloy wire reaches the yield limit, internal microcracks begin to initiate and expand;

[0141] Acoustic emission detection technology is used to monitor the time and location of crack formation in real time, and X-ray diffraction is used to analyze the lattice distortion inside the sample to determine the critical point of microcrack formation;

[0142] By analyzing the damage evolution process of titanium alloy, the fracture characteristics are obtained and the fatigue life of the material is predicted. This step provides a scientific basis for subsequent fracture behavior analysis and provides feedback data for optimizing material composition and process.

[0143] S7. Perform fracture mechanism analysis and fracture morphology characterization based on fracture characteristics to obtain fracture mechanism data.

[0144] In this embodiment, after the sample is broken, the fracture morphology is observed by scanning electron microscopy (SEM) to analyze the fracture mode, such as ductile fracture, brittle fracture or mixed fracture. In addition, the chemical composition distribution of the fracture is detected by X-ray energy dispersive spectrometer (EDS) to determine whether there is material segregation or inclusions affecting the fracture characteristics. Combined with the fracture mechanics analysis method, the fracture toughness parameters (such as K_IC) of the material are calculated to further evaluate the tensile properties of the titanium alloy wire. This step not only verifies the accuracy of the test data, but also reveals the fracture mechanism of the material, providing an important reference for subsequent process optimization and material selection.

[0145] S8. Based on stress-strain data, fracture characteristics, and fracture mechanism data, a dynamic damage evolution model is constructed to predict the tensile properties of materials under different loads and loading rates.

[0146] In this embodiment, the dynamic damage evolution model includes:

[0147] Data correction damage model based on dynamic tensile load increment control method;

[0148] Analytical model of the relationship between fracture characteristics and loading rate;

[0149] Model for predicting failure behavior of titanium alloy wire.

[0150] In this embodiment,

[0151] Data Correction Damage Model:

[0152] In the above steps S4 and S5, we used the dynamic tensile load increment control method to gradually increase the loading rate to improve the test accuracy. This provided us with detailed data under different stress-strain states. In this step, we used this data to modify and optimize the traditional damage mechanics model.

[0153] Assuming that the damage accumulation of the material is increasing during the loading process, we can adjust the calculation formula of the damage index based on the stress-strain curve obtained previously. Over time The evolution of can be expressed by the following formula:

[0154] ;

[0155] It's time The damage index at that time.

[0156] It is at the moment The stress during .

[0157] is the yield strength of the material.

[0158] It is the attenuation constant of the damage index, which reflects the damage evolution characteristics of the material under different loading conditions.

[0159] It is a correction factor related to the dynamic loading increment control method, which describes the damage correction during the loading process. It depends on the relationship between the loading rate and the stress increment in the previous step.

[0160] We can dynamically modify the damage evolution process, especially in the post-yield and high load increment control stages.

[0161] Analysis model of the relationship between fracture characteristics and loading rate:

[0162] In the previous step S6, we have obtained the crack extension of the sample under different loading conditions through microcrack monitoring technology. Based on these crack extension data and the stress-strain data obtained previously, we can combine the Paris law to establish a relationship model between crack extension rate and loading rate:

[0163] ;

[0164] is the crack growth rate.

[0165] is the magnitude of the stress intensity factor.

[0166] and is a constant related to material properties.

[0167] is the threshold for crack growth.

[0168] is a function of time and represents the correction term of the stress intensity factor generated by the dynamic load increment control method, which is related to the stress fluctuation and rate change during the loading process.

[0169] This revised crack growth model can more accurately predict the crack growth rate of titanium alloy wire under different loading conditions, and then calculate the failure time of the material.

[0170] Model for predicting failure behavior of titanium alloy wire:

[0171] We can predict the failure behavior of titanium alloy wire under different working conditions. These prediction results can provide assistance for engineering design to ensure the safe service life of titanium alloy wire.

[0172] The failure behavior model is:

[0173] ;

[0174] in,

[0175] is the failure time of the material.

[0176] is the fracture stress of the material.

[0177] is a constant related to the stress-strain relationship of the material.

[0178] is the correction factor associated with the dynamic loading increment control method.

[0179] This formula can predict the failure time and fracture location of the material under actual working conditions, and further provide reliable life prediction for the application of titanium alloy wire.

[0180] In this step, we built a comprehensive prediction model for dynamic damage evolution by combining the aforementioned dynamic load increment control method, stress-strain data, and microcrack monitoring. This model can accurately describe and predict the damage accumulation and failure behavior of titanium alloy wire under different loading conditions, thereby providing more accurate material performance evaluation and optimization solutions for engineering practice.

[0181] Embodiment 2:

[0182] This embodiment also provides a computer device, which is applicable to a method for detecting the tensile properties of a titanium alloy wire, and includes a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to implement a method for detecting the tensile properties of a titanium alloy wire as proposed in the above embodiment.

[0183] This embodiment further provides a storage medium on which a computer program is stored. When the program is executed by a processor, a method for detecting the tensile properties of a titanium alloy wire as proposed in the above embodiment is implemented.

[0184] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covered on the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0185] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0186] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0187] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk case (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0188] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit with a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit with a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0189] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for detecting the tensile properties of titanium alloy wire, characterized in that: The following steps are involved: S1. Prepare the sample and pre-test the microstructure of titanium alloy wire to provide preliminary material information for tensile performance testing; S2. Perform pre-tension stress distribution equalization treatment on the specimen; S3. Determine the area where local plastic deformation may occur in the specimen and perform precise positioning; S4. After locating the area where local plastic deformation may occur in the specimen, dynamic tensile load increment control is performed, the load is loaded at a constant rate before the yield point, and the loading rate is gradually increased after the yield point to obtain stress-strain data; S5. After obtaining stress-strain data, displacement field analysis is introduced to perform data correction; S6. After the sample enters the plastic deformation stage, the damage evolution characteristics of the material are determined by microcrack monitoring technology to obtain the fracture characteristics; S7. Perform fracture mechanism analysis and fracture morphology characterization based on fracture characteristics to obtain fracture mechanism data; S8. Based on stress-strain data, fracture characteristics, and fracture mechanism data, a dynamic damage evolution model is constructed to predict the tensile properties of materials under different loads and loading rates. In the step S2, when performing the pre-tensioning stress distribution equalization process, the stress state of the sample is firstly modeled; In order to eliminate the residual stress introduced in the specimen during the manufacturing process, it is assumed that the distribution of the initial residual stress of the specimen during the pre-stretching process is an uneven stress field, and as the pre-stretching proceeds, the residual stress gradually decreases and tends to a balanced state; this process is described by the initial stress distribution model, the stress distribution model after pre-stretching, and the balanced stress state model; In step S8, the dynamic damage evolution model includes: Data correction damage model based on dynamic tensile load increment control method; Analytical model of the relationship between fracture characteristics and loading rate; Model for predicting failure behavior of titanium alloy wire.

2. The method for detecting the tensile properties of a titanium alloy wire according to claim 1, characterized in that: The initial stress distribution model is used to describe the inhomogeneity of the initial stress distribution in three-dimensional space, and the residual stress is concentrated on the surface or internal area of ​​the specimen; The initial stress distribution model is as follows: ； in, Indicates that the sample is in position Initial residual stress at is the maximum value of the initial residual stress; It is an attenuation factor related to material processing, which determines the attenuation rate of residual stress in space; is the spatial coordinate inside the specimen.

3. The method for detecting the tensile properties of a titanium alloy wire according to claim 1, characterized in that: The stress distribution model after pre-stretching is as follows: ； in, Indicates at time When the sample is at position stress at It is an attenuation factor related to material processing, which determines the attenuation rate of residual stress in space; is a time constant that describes the decay rate of stress over time during pre-stretching; It is the time of pre-stretching treatment; This model is used to show that over time As time goes by, the stress in the specimen tends to be evenly distributed, and the intensity of the residual stress gradually decreases until it reaches a predetermined equilibrium state.

4. The method for detecting the tensile properties of a titanium alloy wire according to claim 1, characterized in that: The equalized stress state model is as follows: ； Indicates the balanced stress distribution after pre-stretching treatment; It means that the residual stress is finally reduced to half of the initial value and reaches a balanced state; It is an attenuation factor related to material processing, which determines the attenuation rate of residual stress in space; After the specimen has been fully pre-stretched, the stress inside the material tends to be uniform.

5. The method for detecting the tensile properties of a titanium alloy wire according to claim 1, characterized in that: In step S3, the method for determining the area where local plastic deformation may occur includes: Use digital imaging technology to perform high-precision full-field strain measurement on the sample surface, and combine finite element analysis to predict strain concentration areas; If an obvious local strain concentration area is detected, the microstructure observation results are compared to determine whether the abnormal deformation is caused by defects, and the sample sampling position is adjusted.

6. The method for detecting the tensile properties of a titanium alloy wire according to claim 1, characterized in that: In step S4, the dynamic tensile load increment control includes: In the initial stage of the material, a constant loading rate of 5% lower than the material yield strength is used per unit time to ensure that the relationship between stress and strain can change linearly; the loading rate is within the elastic region of the titanium alloy, and 5% to 15% of the material yield strength is selected as the loading rate per unit time to ensure that before the yield strength is reached, the specimen is not affected by stress concentration where the local stress exceeds 150%-200% of the material yield strength; Once the material enters the yield stage, the loading rate is gradually increased; as plastic deformation occurs, the material begins to have the ability to withstand deformation exceeding 5%-10% plastic deformation, thereby ensuring that stress-strain data are captured during the tensile test by gradually increasing the loading rate.

7. The method for detecting the tensile properties of a titanium alloy wire according to claim 1, characterized in that: In step S5, during the stretching process, the clamping method of the sample leads to stress concentration at the end, which affects the measurement accuracy. During the displacement field analysis, the displacement-stress relationship is dynamically corrected: Use a high-precision laser rangefinder or optical measuring instrument to monitor the deformation displacement of the sample in real time during loading, and calculate and correct the measurement error caused by clamping; High-precision strain gauges are used to measure local strain at different locations and compared with the overall tensile curve to adjust the accuracy of the stress-strain curve.

8. The method for detecting the tensile properties of a titanium alloy wire according to claim 1, characterized in that: In step S6, when the titanium alloy wire reaches the yield limit, internal microcracks begin to initiate and expand; Acoustic emission detection technology is used to monitor the time and location of crack formation in real time, and X-ray diffraction is used to analyze the lattice distortion inside the sample to determine the critical point of microcrack formation; By analyzing the damage evolution process of titanium alloy, the fracture characteristics are obtained and the fatigue life of the material is predicted.

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